The invention relates to a process and an arrangement for piecing an air-spun yarn wherein the new yarn end which is produced by the resuming of the spinning operation is taken up and fed to a yarn connecting device for producing a yarn connection between this new yarn end and an old yarn end withdrawn from a partially wound spool.
From German Published Examined Patent application No. (DE-A) 36 11 050, it is known to feed two yarns made of slivers, which were only prestrengthened by means of pneumatic false-twist spinning, as a double yarn, to a splicing arrangement and to splice them there with a double yarn wound off a wind-up spool. A yarn storage device is connected in front of the splicer. Both are part of a movable servicing device. For the emptying of the yarn storage device, the partially wound spool is temporarily driven at a higher speed, after the splicing. The storage device itself is constructed as a simple suction pipe which can take in only one loop.
It was also known from British application No. (GB-A) 21 36 462 to construct a yarn storage device in the form of several suction pipes, which can be activated successively and which serve for receiving a yarn quantity which occurs during a splicing operation when the delivery is not reduced. In this yarn storage device, several loops form behind one another, the individual suction pipes being controlled by a slide valve.
It was also known from British Published Patent application No. (GB-A) 21 36 461 to provide a yarn storage device for a broken yarn in the form of a roller, which is subjected to suction, on which the continuously supplied yarn is deposited in the form of loops.
An object of the invention is to provide a process of the initially mentioned type which can be used for the very high yarn delivery speeds which are possible during air spinning, particularly for only prestrengthened double yarns.
This object is achieved in that the new yarn end is gripped and guided to the yarn connecting device, in which case it is brought into the range of action of a yarn storage device, which is arranged in front of the yarn connecting device and can be activated when the yarn connecting device is operated. The yarn storage device stores the supplied yarn in several loops in such a manner that, during or after the yarn connecting, the continuously supplied yarn is still received by the yarn storage device for so long until the excessive yarn length, present between the inlet of the yarn storage device and the partially wound spool, is used up by means of driving the partially wound spool at a winding speed that is higher than the operational speed.
As a result of the fact that the yarn storage device will be activated only when it is required, specifically when the connecting of the yarn, particularly a splicing, is carried out, the yarn quantity which must be stored by it is limited. Only that quantity of yarn must be stored that occurs during the stoppage and the subsequent emptying of the storage device. This means that the storage capacity must be slightly larger than the capacity required for the pure stoppage time during the splicing. If, subsequently, the storage device is emptied at very high winding speeds, such as winding speeds which are twice as high as the operational speed, the excess capacity of the yarn storage device may also be maintained relatively low. In the case of embodiments used in practice, it is sufficient for the storage capacity to be at least 1.15 times and preferably 1.2 times to 1.4 times the yarn length supplied by the respective spinning arrangement during the stoppage time while the yarn connecting device is operated.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.